There exist many types of extender cards for testing and debugging various computer components, such as video cards, sound cards, etc. Such components usually have two groups of connectors. One of these groups is used for connection to the main part of the computer, for example, to the motherboard. Another group is used for connection to the different types of the test components (peripheral devices). Most of the peripheral devices, like video cards, sound cards, network cards and etc., have a group of connectors located on the bracket side (front side) of these cards for the external cable connection.
Various extender (extension) cards play a significant role in the computer industry. Such devices make possible debugging (testing) different components inside the working computer unit. They allow access with test equipment (like oscilloscope, logic analyzer and etc.) to the different places of the tested components during real-time operations and give a possibility of hot-swap testing components without shutting-down a computer unit power.
Many similar devices are manufactured by different firms, for example [1, 3]. These extender cards usually consist of the printed circuit board (PCB) and two electrical connector groups. The first group of these connectors is intended for connection to the system motherboard. Such a motherboard is installed in a computer system unit. The second group of these connectors is intended for the plug-in tested component (peripheral device).
These extender cards are of two types: passive or active. The passive extender cards are free from any electronic circuits and connect all matching connectors of both groups by printed wires. The active extender cards have various logical circuits on the cards. The active extender cards make it possible to insert the test component into the extender card socket and to extract said component without shutting-down the power of the computer unit.
Practically, on all known extender cards, (for example, [2]) these two groups of connectors are located on the PCB and are oriented in parallel to one another in the extender card plane.
Usually each group of the apparatus (types and sizes of a computer unit, types and sizes of test components etc.) has corresponding special types of extender cards.
Every extender card produces an additional signal propagation delay, and this additional signal propagation delay disturbs the normal operation of modern computers. It relates to the fast interface signals, such as AGP, PCI-X, PCI express and other fast interfaces. Decreasing the height of the extender card makes the access to the components under test more difficult. In addition, decreasing the height of the extender makes impossible plug-in cables to the front side connector group (bracket side) of the test component. The minimum height of the extender card is dictated by the size of the computer system unit (computer case). In most cases it is significantly large.
In the last few years many new extender cards have been made for various interfaces and computer system units [4, 5]. The majority of these extender cards have small height and even have no possibility for installing the bracket, for example AGPROIX [5], etc. This solution helps to minimize additional signal propagation delay on the extender card, but at the same time the system including this type of extender card and tested component becomes mechanically unstable and there is no possibility to plug-in external cable to the front side connector group (placed on the bracket side) of the test component.
Known patents offer various ways of this problem's alleviation.
In U.S. Pat. Nos. 6,567,870 [6] and 6,356,959 [7] it is offered to use the partial-height PCI cards (for example a half-height or one-third-height card), that can be stacked edge-to-edge and to attach a similar card perpendicular to the main assembled extender card.
This requires having a collection of such cards and may be used if it needs two-three cards only. Otherwise this combination is mechanically unstable. On the other hand, this combination doesn't allow for decreasing the signal propagation delays.
U.S. Pat. No. 5,967,814 [8] protects the unit, allowing to dispose the computer plates in view of the “open book”. This way allows providing light access to various points placed on the computer plates, but requires using cables for connection between these plates, which increases the signal propagation delay. The necessity of additional special apparatus prevents the use of this patent by small customers.
In this case, as in U.S. Pat. No. 5,967,796 [9], special jig limits of the application area are used. Moreover, the use of the special cable increases the signal propagation delays.
Patents CA2083017 [10], CA1241396 [11] and CA2386464 [12] display a small mechanical improvements. They promote computer testing, but don't solve the problem of the propagation delay.
Patent CA2328231 [13] offers system that makers only easier plug-in test devices and removing them.
The present invention gives the possibility of full testing [including plug-in cables to the front side connector group (bracket side) of the tested peripheral device] and the convenience of work with the peripheral device without significantly increasing signal propagation delays.
The present invention is equally suitable for use for the different type of computers (computers where the extender card sits in perpendicular to the motherboard or computers where the extender card is parallel to the motherboard).